Elemental dispersion and stable isotope fractionation during reactive fluid-flow and fluid immiscibility in the Bufa del Diente aureole, NE-Mexico: evidence from radiographies and Li, B, Sr, Nd, and Pb isotope systematics

Romer, Rolf L.; Heinrich, Wilhelm; Schröder-Smeibidl, B.; Meixner, Anette; Fischer, Carl-Otto; Schulz, Cathrin

doi:10.1007/s00410-005-0656-9

Cited by 106 publications

(34 citation statements)

References 79 publications

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“…Pb from rock powders was separated using anion exchange resin Bio-Rad AG1-X8 applying the HCl-HBr technique described by Romer et al (2005) (Jaffey et al, 1971;Steiger and Jäger, 1977).…”

Section: Bulk-rock Sr-nd-hf-pb Isotope Compositionmentioning

confidence: 99%

Between carbonatite and lamproite—Diamondiferous Torngat ultramafic lamprophyres formed by carbonate-fluxed melting of cratonic MARID-type metasomes

Tappe

Foley

Kjarsgaard

et al. 2008

Geochimica et Cosmochimica Acta

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256

104

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New U-Pb perovskite ages reveal that diamondiferous ultramafic lamprophyre magmas erupted through the Archean crust of northern Labrador and Quebec (eastern Canada) .2). These contrasting isotopic characteristics of aillikites/carbonatites and mela-aillikites, along with subtle differences in their modal carbonate, SiO 2 , Al 2 O 3 , Na 2 O, Cs-Rb, and Zr-Hf contents, are consistent with two distinctive metasomatic assemblages of different age in the mantle magma source region.Integration of petrologic, geochemical, and isotopic information leads us to propose that the isotopically enriched component originated from a reduced phlogopite-richterite-Ti-oxide dominated source assemblage that is reminiscent of MARID suite xenoliths. In contrast, the isotopically depleted component was derived from a more oxidized phlogopite-carbonate dominated source assemblage. We argue that low-degree CO 2 -rich potassic silicate melts from the convective upper mantle were preferentially channelled into an older, pre-existing MARID-type vein network at the base of the North Atlantic craton lithosphere, where they froze to form new phlogopite-carbonate dominated veins. Continued stretching and thinning of the cratonic lithosphere during the Late Neoproterozoic remobilized the carbonate-rich vein material and induced volatile-fluxed fusion of the MARID-type veins and the cold peridotite substrate. Isotopic modelling suggests that only 5-12% trace element contribution from such geochemically extreme MARID-type material is required to produce the observed compositional shift from the isotopically most depleted aillikites/carbonatites towards enriched mela-aillikites.We conclude that cold cratonic mantle lithosphere can host several generations of contrasting vein assemblages, and that each may have formed during past tectonic and magmatic events under distinctively different physicochemical conditions. Although cratonic MARID-type and carbonate-bearing veins in peridotite can be the respective sources for lamproite and carbonatite magmas when present as the sole metasome, their concomitant fusion in a complex source region may give rise to a whole new variety of deep volatile-rich magmas and we suggest that orangeites (formerly Group 2 kimberlites), kamafugites, and certain types of ultramafic lamprophyre are formed in this manner.

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“…Pb from rock powders was separated using anion exchange resin Bio-Rad AG1-X8 applying the HCl-HBr technique described by Romer et al (2005) (Jaffey et al, 1971;Steiger and Jäger, 1977).…”

Section: Bulk-rock Sr-nd-hf-pb Isotope Compositionmentioning

confidence: 99%

Between carbonatite and lamproite—Diamondiferous Torngat ultramafic lamprophyres formed by carbonate-fluxed melting of cratonic MARID-type metasomes

Tappe

Foley

Kjarsgaard

et al. 2008

Geochimica et Cosmochimica Acta

Self Cite

256

104

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“…Digested samples were dried and taken up in 6 N HCl. Sr and Nd were separated and purified as described in the study by Romer et al (2005). Sr isotopic composition was determined on a VG54 Sector multi-collector mass spectrometer at GFZ Potsdam.…”

Section: Sr Nd and Pb Isotopesmentioning

confidence: 99%

“…Pb was separated using a HBr-HCl ion-exchange procedure (cf. Romer et al 2005) and analyzed on a Finnigan MAT 262 multi-collector mass-spectrometer. Pb isotope data were corrected for mass discrimination with 0.1% A.M.U.…”

Section: Sr Nd and Pb Isotopesmentioning

confidence: 99%

“…The initial isotopic compositions were determined for T = 240 Ma, which represents the time of the collision between the North China and Yangtze plates (Li et al 1993). For analytical details, see Romer et al (2005) b Analyzed using dynamic multicollection using a VG content of 18 lg/g and a d 7 Li value of -6.9 %, whereas the latter has 7.7 lg/g Li and a d 7 Li value of -0.4 %, suggesting strong Li isotope fractionation between eclogite and amphibolite (Table 4; Fig. 6).…”

Section: Sample Sets 3 Andmentioning

confidence: 99%

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Fluid/rock interaction and mass transfer in continental subduction zones: constraints from trace elements and isotopes (Li, B, O, Sr, Nd, Pb) in UHP rocks from the Chinese Continental Scientific Drilling Program, Sulu, East China

Xiao

Hoefs²,

Hou

et al. 2011

Contrib Mineral Petrol

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In order to better understand the role of fluids during subduction and subsequent exhumation, we have investigated whole-rock and mineral chemistry (major and trace elements) and Li, B as well as O, Sr, Nd, Pb isotopes on selected continuous drill-core profiles through contrasting lithological boundaries from the Chinese Continental Scientific Drilling Program (CCSD) in Sulu, China. Four carefully selected sample sets have been chosen to investigate geochemical changes as a result of fluid mobilization during dehydration, peak metamorphism, and exhumation of deeply subducted continental crust. Our data reveal that while O and Sr-Nd-Pb isotopic compositions remain more or less unchanged, significant Li and/or B isotope fractionations occur between different lithologies that are in close contact during various metamorphic stages. Samples that are supposed to represent prograde dehydration as indicated by veins formed at high pressures (HP) are characterized by element patterns of highly fluid-mobile elements in the veins that are complementary to those of the host eclogite. A second sample set represents a UHP metamorphic crustal eclogite that is separated from a garnet peridotite by a thin transitional interface. Garnet peridotite and eclogite are characterized by a [10% difference in MgO, which, together with the presence of abundant hydroxyl-bearing minerals and compositionally different clinopyroxene grains demonstrate that both rocks have been derived from different sources that have been tectonically juxtaposed during subduction, and that hydrous silicate-rich fluids have been added from the subducting slab to the mantle. Two additional sample sets, comprising retrograde amphibolite and relatively fresh eclogite, demonstrate that besides external fluids, internal fluids can be responsible for the formation of amphibolite. Li and B concentrations and isotopic compositions point to losses and isotopic fractionation during progressive dehydration. On the other hand, fluids with isotopically heavier Li and B are added during retrogression. On a small scale, mantle-derived rocks may be significantly metasomatized by fluids derived from the subducted slab. Our study indicates that during high-grade metamorphism, Li and B may show different patterns of enrichment and of isotopic fractionation.

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“…Digested samples were dried and taken up in 6N HCl. Sr and Nd were separated and purified using ion-exchange chromatography as described in Romer et al (2005). Pb was separated using the HBr-HCl ion-exchange procedure as described in Romer et al (2005) …”

Section: Figuresmentioning

confidence: 99%

Origin of fayalite granitoids: New insights from the Cobquecura Pluton, Chile, and its metapelitic xenoliths

Vásquez¹,

Glodny²,

Franz³

et al. 2009

Lithos

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Fayalite granitoids of the Cobquecura Pluton, Central Chile, occur in an active continental margin setting, which is unusual for such rocks. They are closely associated with gabbros, and both lithologies contain hercynite-rich, Fe-rich metapelitic xenoliths. The primitive magmas of the Cobquecura Pluton are derived from a mafic source, similar to the regional subarc subcontinental mantle. Sr-Nd-Pb isotope data demonstrate that crustal contributions were important in the petrogenesis of the fayalite granitoids. The crustal contribution, however, does not consist of rocks similar to the regionally exposed Paleozoic basement rocks, but rather resembles partial melts derived from metapelitic rocks at depth. The corresponding restites are the hercynite-rich xenoliths. A relatively high content of rare earth elements and high field strength elements in the fayalite granitoids is linked to selective assimilation of crust. This is evident from the abundant xenoliths that are entrained in the fayalite granitoids, and whose leucosomes are rich in accessory minerals carrying these elements. Such Fe-rich rocks similar to the hercynite-rich xenoliths could have acted as a chemical buffer keeping the oxygen fugacity low, which is crucial for the generation of fayalite bearing granitoids.

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Elemental dispersion and stable isotope fractionation during reactive fluid-flow and fluid immiscibility in the Bufa del Diente aureole, NE-Mexico: evidence from radiographies and Li, B, Sr, Nd, and Pb isotope systematics

Cited by 106 publications

References 79 publications

Between carbonatite and lamproite—Diamondiferous Torngat ultramafic lamprophyres formed by carbonate-fluxed melting of cratonic MARID-type metasomes

Between carbonatite and lamproite—Diamondiferous Torngat ultramafic lamprophyres formed by carbonate-fluxed melting of cratonic MARID-type metasomes

Fluid/rock interaction and mass transfer in continental subduction zones: constraints from trace elements and isotopes (Li, B, O, Sr, Nd, Pb) in UHP rocks from the Chinese Continental Scientific Drilling Program, Sulu, East China

Origin of fayalite granitoids: New insights from the Cobquecura Pluton, Chile, and its metapelitic xenoliths

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